1. Field of the Invention
The present invention relates to a light emitting element comprising an organic thin film layer as a light emitting layer, and a production process thereof.
2. Description of the Related Art
There has been known an organic electroluminescence panel in which an organic thin film layer as a light emitting layer is sandwiched between a positive electrode and a negative electrode which were arranged in a stripe shape to mutually orthogonalized directions, and picture images are displayed by making the light emitting layers emit light by impressing voltage between the positive electrodes and negative electrodes. In a so-called simple matrix drive, fixed pixels formed at intersecting points of the positive electrodes and negative electrodes emit light by impressing signal voltage on either of the positive electrodes or negative electrodes while sequentially scanning the other electrodes and arbitrary picture images can be displayed.
However, the light emitting times of the respective pixels in one flame cannot but be shortened because of line-sequential drive in the simple matrix drive, and high momentary luminance is required in order to obtain a picture image having a fixed brightness. Accordingly, the deterioration of an organic thin film because of the heat release and light emission of light emitting layers is apt to occur, and as a result, the life of light emitting elements is shortened.
The object of the present invention is to provide a light emitting element capable of suppressing the deterioration of an organic thin film layer as light emitting layers and a production process thereof.
To solve the problem, the light emitting element comprise a light emitting body emitting light by impressing voltage, and a rectifier connected in series with the light emitting body. The emitting body contains an organic thin film layer and the rectifier has an organic thin film.
According to the invention, since the light emitting body and the rectifier connected in series are provided, the light emitting element constitutes a close circuit in the inside by the valve action of the rectifier at impressing reverse voltage, charges remaining in a capacitor which the light emitting body has are run in the light emitting layers, and the light emission of the light emitting body is kept during the time. Accordingly, the light emitting time in one scanning can be increased by a portion of a residual light emitting caused by the discharged electric charge of a capacitor, momentary luminance can be lowered, therefore the deterioration of the light emitting body is suppressed, and the long life light emitting element is obtained.
The organic thin film may be composed of the same material as the organic thin film layer. In this case, since steps of forming the insulator layer and the organic thin film layer can be commonized, the production steps of the light emitting element can be simplified and production cost can be reduced.
The respective layers constituting the rectifier and the respective layers constituting the light emitting body may be provided at a position in which they are mutually piled up. In this case, since it is not required to secure a proprietary region for the rectifier, the area of the region contributing as the light emitting layers is not suppressed, and for example, the aperture ratio as a display panel can be enlarged.
The production process of a light emitting element of the present invention comprise a light emitting body emitting light by impressing voltage, and a rectifier having an organic thin film and connected in series with the light emitting body. The production process includes a step of forming an organic thin film layer contained in the light emitting body and a step of forming an organic thin film of the rectifier.
According to the invention, since the light emitting body and the rectifier connected in series are provided, the light emitting time in one scanning can be increased at impressing reverse voltage by a portion of a residual light emitting caused by the discharged electric charge of a capacitor because of the valve action of the rectifier, momentary luminance can be lowered, therefore the deterioration of the light emitting body is suppressed, and the long life light emitting element is obtained.
The organic thin film of the rectifier may be composed of the same material as the organic thin film layer.
In this case, since the organic thin film of the rectifier is composed of the same material as the organic thin film layer, the simplification of steps and cost down can be designed.
The organic thin film later and the organic thin film of the rectifier may be formed using the same film forming method.
In this case, since the organic thin film later and the organic thin film are formed using the same film forming method, the simplification of steps and the commonization of a film forming apparatus are designed and production cost can be reduced.
In this case, an evaporation method can be used and a spin coat method can be used as the film forming methods of the organic thin film later and the insulator layer.